**Core Concept**
Obsessive-compulsive disorder (OCD) and related conditions, such as trichotillomania (hair pulling) and onychophagia (nail biting), are characterized by repetitive behaviors or mental acts that an individual feels compelled to perform. These conditions often involve abnormalities in the brain's reward and motor control systems.

**Why the Correct Answer is Right**
Selective serotonin reuptake inhibitors (SSRIs), particularly fluoxetine, have been shown to be effective in treating OCD and related conditions. SSRIs work by increasing the levels of serotonin in the synaptic cleft, which helps to reduce the frequency and severity of obsessive thoughts and compulsive behaviors. In the case of trichotillomania and onychophagia, SSRIs may help to reduce the urge to engage in these repetitive behaviors.

**Why Each Wrong Option is Incorrect**
**Option A:** While benzodiazepines can be used to treat anxiety disorders, they are not typically effective for treating OCD or related conditions.
**Option B:** Antipsychotics may be used to treat certain symptoms of OCD, but they are not the first-line treatment for this condition.
**Option C:** Mood stabilizers, such as lithium, are primarily used to treat bipolar disorder and are not typically effective for treating OCD or related conditions.

**Clinical Pearl / High-Yield Fact**
SSRIs can take several weeks to start working, so patients with OCD or related conditions should be encouraged to continue treatment even if they don't see immediate results.

**Correct Answer:** C. Antipsychotics may be used to treat certain symptoms of OCD, but they are not the first-line treatment for this condition.